Gas turbines generally operate by combusting a fuel and air mixture in one or more combustors to create a high-energy combustion gas that passes through a turbine, thereby causing a turbine rotor shaft to rotate. The rotational energy of the rotor shaft may be converted to electrical energy via a generator coupled to the rotor shaft. Each combustor generally includes fuel nozzles that provide for delivery of the fuel and air upstream of a combustion chamber, using premixing of the fuel and air as a means to keep nitrogen oxide (NOx) emissions low.
Gaseous fuels, such as natural gas, often are employed as a combustible fluid in gas turbine engines used to generate electricity. In some instances, it may be desirable for the combustion system to be able to combust liquid fuels, such as distillate oil. A configuration with both gas and liquid fuel capability is called a “dual-fuel” combustion system. Certain dual-fuel type combustion systems operate using multiple dual-fuel primary or outer fuel nozzles annularly arranged around a center fuel nozzle. The outer dual-fuel fuel nozzles include liquid fuel injection cartridges that are breach loaded through an end cover of the combustor and that provide liquid fuel which may be used to start the engine, increase load and bring it up to full operating speed.